Numerous starting systems have been used in diesel engines to facilitate starting. For example, a highly volatile fluid such as ether is typically injected into the engine intake during the initial "cranking" of the engine. Previous systems have used a metered quantity of starting fluid which is continuously injected into the engine during the starting procedure. One such system is disclosed in U.S. Pat. No. 3,960,131, issued June 1, 1976, in the name of Davis. In that patent, a fluid cylinder of ether is connected to a valve which injects ether through a conduit to an atomizer readily secured to the engine. Further, the starter solenoid is connected to a timing switch which is normally opened and closed only after a heating resistor causes a bi-metal switch arm to snap to the open or closed position. In operation, as the ignition switch is closed, an electric circuit is completed through the heating resistor. The heating of the resistor causes the bi-metal switch arm to close and energize the solenoid of the valve into which a quantity of starting fluid is measured. Each time the bi-metal switch arm opens, the valve solenoid becomes de-energized and the previous metered quantity of fluid is injected through the conduit to the engine.
One of the problems with the above system is that a heating element is used to open and close a bi-metal switch which is subject to ambient temperatures which can lead to inaccurate control. This results in a nonuniform time interval in which the quantity of ether is injected into the engine. This tends to provide too much ether into the engine and causes engine damage.